The present invention relates to a new process for the production of alkylidene diesters at high selectivities and yields and, more particularly, to the high yield production of ethylidene diacetate which is readily convertible to vinyl acetate.
It is known to produce vinyl esters of the type having the general formula ##STR1## in which R, R.sub.1 and R.sub.3 may be either hydrogen or alkyl and R.sub.2 is an alkyl group. The oldest commercial process for producing vinyl acetate, the most important of these esters, for example, involves the reaction of acetaldehyde and acetic anhydride to produce ethylidene diacetate which is then catalytically decomposed to give vinyl acetate. Because of the high cost of producing the acetic anhydride starting material, however, most vinyl acetate now made commercially is produced by processes which start with either ethylene or acetylene and with acetic acid. A method is described in copending application Serial No. 591,919, whereby the ethylidene diacetate can be produced directly from more readily available raw materials than those of the prior art. The diester can then be catalytically cracked to the vinyl ester produced, two moles of acetic acid are simultaneously produced, one in the synthesis of the diester and one in its conversion, and no acetic acid is consumed in the process. This process, while quite satisfactory in most respects, exhibits coproduction of acetic anhydride with ethylidene diacetate which may be desirable in some situations. The present invention provides a process which gives improved selectivity and yield of diesters, minimizing the coproduction of acetic anhydride.